0: the number of possible scenarios under which my credential could have expired on January 1, 2005.

I had an internship credential that expired in 9/03, a temporary waiver that expired 1/04, and a full credential that expires on 1/09.  The district tells me that I have a full (5-year) credential that expired on 1/05.  In order for this to happen, I would have had to have earned my credential when I was a 19-year-old junior in college.  They are threatening to fire me and say they cannot pay me until the issue is resolved.

I hate this job.

edit: I don't hate this job, I hate my bosses.  All of them.  Here's a clue for educational policy - if you hear that the school district or the teachers' unions are fighting it, it's most likely good.  Some of their issues (No Child Left Behind is bad, there's not enough funding for schools in general) are legit.  But mostly they just operate to perpetuate their own incompetance.  The reasons schools have issues, first of all, is parents who don't prepare their children to come to school and behave and learn.  The second reason is that too much of the budget goes to too many incompetant administrators. The third is that good teachers are impossible to recruit, partly cause funding sucks, party cause the administrators are incompetant, and partly because the teachers' union fights every reform that would make recruitment better.  I hate the people that make me not have fun in this job.